Naslund Chapter 1 Analysis
2023-04-19
Chapter 1 Sampling scheme
We sampled 4 sites over at least one 24 hr period. We installed 25 ebullition traps across 5 transects in each impoundment. Every 3 hours, we recorded the volume of gas accumulated in each ebullition trap and took a diffusive flux measurement immediately adjacent to 10 if the ebullition traps across the impoundment. To determine impoundment area, I digitized the impoundments using high resolution (0.5 ft) orthoimagery captured during the leaf off period. Pick has a beaver dam on the inlet stream and I delineated only to the beaver dam.
| Site | Area (km2) | Max Depth (m) | Mean Depth (m) | Residence Time (days) | Dates Sampled |
|---|---|---|---|---|---|
| Deans | 0.0041 | 3.52 | 2.03 | 46 | 8/16/22 - 8/17/22 8/30/22 - 8/31/22 |
| Sister 3 | 0.0012 | 2.27 | 1.25 | 20 | 8/22/22 - 8/23/22 |
| Catfish | 0.0018 | 1.98 | 0.80 | 19 | 9/06/22 - 9/07/22 9/18/22 - 9/19/22 |
| Pick | 0.0077 | 3.80 | 1.58 | 45 | 8/22/22 - 8/23/22 |
1.1 Dissolved oxygen
We recorded dissolved oxygen every 15 minutes 0.25 m below the surface in every impoundment. From 6/20/22 to 7/13/22, we also recorded dissolved oxygen 0.1m from the bottom of Pick in the deepest location in the impoundment. Because dissolved oxygen was consistently 0 mg/L, we reallocated our oxygen sensors and installed both a top and bottom DO sensor in Sister 3.
1.4 Dissolved gas concentrations
I sampled for dissolved gas 0.25 m from the surface of the impoundments, 0.1m from the bottom, in the inlet stream, and in the outlet stream. The dissolved gas samples from Catfish on 9/18/22-9/19/22 were not handled properly, thus those values are excluded from the summaries.
## # A tibble: 20 × 7
## # Groups: Site, Collection.Date [5]
## Site Collection.Date Location CH4_avg_umol CH4_sd CO2_avg_umol CO2_sd
## <chr> <chr> <fct> <dbl> <dbl> <dbl> <dbl>
## 1 Pick 9/13/2022 top 98.7 3.09 560. 8.69
## 2 Deans 8/31/2022 top 0.980 1.32 62.3 7.88
## 3 Sister3 8/23/2022 top 0.849 0.0111 40.3 4.55
## 4 Catfish 9/6/2022 top 0.586 0.00180 138. 5.69
## 5 Deans 8/16/2022 top 0.583 0.0476 107. 3.11
## 6 Pick 9/13/2022 bottom 126. 60.7 635. 161.
## 7 Sister3 8/23/2022 bottom 2.89 0.985 70.0 15.2
## 8 Deans 8/16/2022 bottom 0.883 0.0543 88.9 16.4
## 9 Catfish 9/6/2022 bottom 0.557 0.0686 164. 49.1
## 10 Deans 8/31/2022 bottom 0.290 0.0597 36.6 6.79
## 11 Deans 8/31/2022 inlet 16.9 4.77 377. 99.1
## 12 Pick 9/13/2022 inlet 9.98 1.34 168. 9.29
## 13 Deans 8/16/2022 inlet 9.95 2.86 234. 46.0
## 14 Catfish 9/6/2022 inlet 0.598 0.197 141. 6.10
## 15 Sister3 8/23/2022 inlet 0.0229 0.0000664 75.2 7.54
## 16 Deans 8/31/2022 outlet 4.31 0.936 153. 44.1
## 17 Sister3 8/23/2022 outlet 2.62 0.0720 81.8 8.42
## 18 Catfish 9/6/2022 outlet 1.47 0.410 142. 9.15
## 19 Pick 9/13/2022 outlet 0.365 0.170 160. 25.6
## 20 Deans 8/16/2022 outlet 0.311 0.106 50.2 5.51
1.5 Wind Speed
We took two 15 second averaged windspeed measurements over the course of each diffusive flux measurement. Note different x-axis scales.

1.6 Residence time calculation
I took a point estimate of discharge from the ponds while sampling, but these discharge values gave unrealistic residence times. I instead calculated discharge from a regional regression equation using average annual precipitation and watershed area (Gotvald et al. 2017).